新疆杨在风荷载作用下应力应变

【Abstract】wWw.shuoshilunwen.com The trees in nature is important, it can not only improve the ecological environment, adjust the climate, conserve soil and water; But also he significant effect on improving soil and increasing fertility, wind prevention and sand-fixation, preventing tides and wes struck. Cyclone is one of the worst disasters in natural. Because of the high wind frequency, it always bring the huge losses and hazards to human life and property. Our country is vast in territory, many regions always hit by the storm. Trees destroyed in the storm damage. The destruction of trees will not only cause serious economic loss, even can cause certain degree of casualties, therefore the trees deformation mechani research under wind load is very necessary.According to the relationship between force and displacement, This paper uses retrospective method and measured displacement under known load to calculate the elastic modulus of trees, ignoring the deformation caused by axial and shear force, assuming material is elastic. Using Pro/e 3D drawing software to build the three-dimensional entity model of Populus bolleana and then Performing structure static and dynamic(random vibration) finite element analysis in Ansys workbench. We can obtain stress, strain and displacement changing regularity under static wind and fluctuating wind of Populus bolleana. Comparing the extraction strain, displacement, velocity and acceleration changes in DBH in Ansys workbench post-processing with the values laboratory measured we can find that the calculated data is in consistent with the actual data. Also we can get stress、strain and displacement deformation image and find the damage and deformation regularity that the maximum most appeared in the branches and backbone stems junction connected stems junction under wind load of Populus bolleana. it is because the cross-sectional changes of branches junction easily emerge stress concentration and corner can easily absorb wind. The maximum horizontal displacement mainly appears in treetops place, especially in the aller treetop section.Comparing the stress, strain and displacement value of different structure forms, we find that each value is larger corresponding with the reduction of branch; At the same time, the dangerous point and the maximum place of different structure forms also reveals the destroy order of the whole plant when sufferring more hey wind load; The vibration frequency increases along with the reduction of branch. Unilateral structure has bigger stress, strain and displacement value than symmetric structure. This shows the influence of tree structure form itself on stress, which can provide reference for the future pruning.